$n_{H_2}=\dfrac{7,437}{24,79}=0,3(mol)$
$a)PTHH:2Al+6HCl\to 2AlCl_3+3H_2$
$\Rightarrow n_{Al}=\dfrac{2}{3}n_{H_2}=0,2(mol)$
$\Rightarrow \%m_{Al}=\dfrac{0,2.27}{24,6}.100\%=21,95\%$
$\Rightarrow \%m_{Cu}=100-21,95=78,05\%$
$b)n_{AlCl_3}=n_{Al}=0,2(mol)$
$\Rightarrow m_{AlCl_3}=0,2.133,5=26,7(g)$
$c)n_{HCl}=3n_{Al}=0,6(mol)$
$\Rightarrow C_{M_{HCl}}=\dfrac{0,6}{0,3}=2M$